The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Automobile sunroofs made of glass materials are heavy due to characteristics of the materials such as tempered glass, and are likely to naturally break when impurities remain in the glass materials and to cause damage to humans due to breakage and pieces of broken glass when vehicles are overturned. As an alternative to such glass materials, double-laminated glasses have often been used. However, these materials are still heavy and the manufacturing costs may increase due to complicated manufacturing processes. In addition, polycarbonate (PC) and polymethylmethacrylate (PMMA) have commonly been used as plastic materials. When polycarbonate (PC) is used, hardness may be insufficient, an increase in thickness may be encountered, and scratch and weather resistance may be poor. Polymethylmethacrylate (PMMA) as a replacement for conventional glass materials lacks impact resistance.
Japanese Unexamined Patent Publication No. 2006-212820 discloses a glass fiber sheet having both high light diffusibility and improved light transmissivity, and a method of manufacturing the same. The method includes stacking woven glass fiber fabrics in which a transparent resin composition has a high refractive index in a range of ±0.02, and impregnating the stacked glass fiber fabrics in a thermosetting resin having a norbornene-based backbone to prepare a fiber-reinforced composite. However, when the glass fiber sheet is applied to automobile sunroofs, or the like, the glass fiber sheet remains thin, has insufficient dimensional stability, and transparency may be degraded as the glass fiber sheet grows thick due to a difference in refractive index between glass fibers and the resin composition.
Therefore, there is a desire for transparent composites made of plastic materials which have improved automobile fuel efficiency through lightweight design by replacing the glass materials with the plastic materials, can achieve easier handling characteristics due to reduction in vehicle center of gravity, and shows excellent juddering and dimensional stability during driving due to excellent hardness.